Using CovertPad – Unit Converter android apps you can convert all units easily , just select the unit you want to convert e.g. length, weight, pressure, temperature etc. Type the value for example in length select meter , type 100 and it will show all related units like , 0.1 kms, 10000 cms., 100000 mm etc.

You can also create your own user defined units by using multiplication factor, for an engineer it is very good and must have android apps for calculating many engineering calculations , iterations etc.